Stationary induction apparatus



Dec. 11 1923.

v S. E. JOHANNESEN STATIONARY INDUCTION APPARATUS Filed April 11, 1921 Fig.1.

Inventor":

HisAttorney.

Svand EJoharmesen,

Patented Dec. 11, 1923.

UNITED STATES PATENT OFFICE.

SVEND E. JOHANNESEN, OF PITTSFIELD, MASSACHUSETTS, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

STATIONARY INDUCTION APPARATUS.

Application filed April 11, 1921.

1 all whom it may concern:

Be it known that I, SVEND E. JOHANNE- SEN, a citizen of the United States, residing at Pittsfield, in the county of Berkshire, State of Massachusetts, have invented certain new and useful Improvements in Stationary Induction Apparatus, of which the following is a specification.

My invention relates to stationary induction apparatus having cores of laminated magnetic material; and particularly to that type of apparatus having so-called distributed cores.

The general object of my invention is to provide an improved type of lamination for such apparatus which is economical and which is readily adapted to manufacturing processes.

In distributed core type induction apparatus, it has been the constant aim of designers to so form the core that there will be a maximum amount of iron in the central or winding leg with substantially a minimum mean winding turn surrounding it. It is also desirable at the same time to have the windings conform as far as practicable with the configuration of the magnetic flux in the core so that the apparatus will have low internal reactance.

A core which embodies these features is disclosed in U. S. Letters Patent No. 1,299,953 granted April 8, 1919 in my name. Specifically the immediate object of my present invention is to devise a core lamination suitable for assembly in the core disclosed in my above patent and which may be producedwith a minimum waste of the material from which it is manufactured.

This I accomplish by adapting the laminations for special nested relations so that they may be struck successively by dies from a sheet of stock with substantially no waste or rejected material.

For a more complete understanding of the nature and objects of my invention reference should be had to the following detailed description taken in connection with the accompanying drawing in which:

posed of laminations embodying my inven-' tion. Figs 3 and 4 show the nested relation of the laminar elements to each other in a Fig. 1 is a top plan view, and Fig. 2 is a Serial No. 460,589.

piece of stock from which they are to be out; whlle Fig. 5 shows the assembly of the laminar elements to make a complete lamination for a core section.

7 what diagonally thereacross, (shown in Fig.

5 as a gap) alternate laminations or groups of laminations are arranged so that the gaps run alternately from left to right in one lamination (as shown in Fig. 5) then from right to left in the nextlamination. In this manner a construction having the joints occurring all in one place is avoided; the diagonally cut joints at the same time resulting in smaller core losses than if cut at right angles to the longitudinal dimension of the lamination at such point since the diagonally cut joint has lower flux density thanthe right angular cut.

The laminations composing a section are preferably of such widths as to yield a construction adapted to be dovetailed .with the edges of the other sections to form the central leg without waste pace, save for the central ventilating prismatic passage shown at o in Fig. 1. In all instances however it is preferable to have those portions of the laminar elements which compose the yoke portions of the core proportioned 'so as to yield lower magnetic flux densities in these portions than in the leg portions, as it is in the interests of economy to design transformers to operate with high'fiux densities on its leg which is the complement of fillet 27 and coincides therewith in the nested relation shown in Figs. 3 and 4.

The element 21 also has what is a base to the l. at 30, which in the nested relation is cut to fit over the cut corner 25 of the element 20, there being an extension bounded by the diagonal edge 31 on the base 30 which is the complement of the cut corner 25.

Except for the protruding knob at 33, the diagonal edge of the fillet 27 substantially extends clear to the lower right hand corner of the base of the element 20 such edge however may be slightly ofi'set below the knob in an amount depending on the width to be given the leg of element 21. The extended edge is denoted at 34, and in the nested relation of the elements is the complement of its out corner at 26; but in the assembled relation when forming a lamination as shown in Fig. 5 it is the complement .of cut corner 28 on element 21.

The elements 20 and 21 when nested as shown in Fig, 3 coincide to form a strip of stock of. the magnetic materialfrom which they may be struck by suitable dies.

The showing of nested elements in Fig. 4

is similar to that in Fig. 3 but here each of the elements 20 has a small trapezoidal sliver taken out from the inside edge of its leg. as indicated at 40. The purpose in removing this sliver of material is to produce elements 20 which when assembled with elements 21 will form laminations as shown in Figf-5, having larger window openings w for receiving the winding 15 than i the sliver were not removed. The element 20 shown in Fig. 5 is one having the sliver at 40 removed.

The winding windows w in the laminations formed by the elements 20 and 21 are also generally trapezoidal in shape. It is for this reason that the sliver 40 may be removed to increase the size of the window withoutdetrim'ental effect On the magnetic circuit in the lamination. By removing this trapezoidal sliver more window area is achieved without appreciably increasing the mean length of the magnetic path or materially increasing the reluctance, the cross-sectional area of the assembled laminations being onl decreased'for the comparatively short istance represented by the short base of the trapezoidal sliver 410m Accordingly, it is seen that my invention provides laminar elements adapted to be narrate assembled into the improved cores disclosed in. my aforesaid Letters Patent which are the complements of each other, a base of one l. enveloping a leg of the other whereby they may be nested and struck in succession from sheet stock with substantially no waste except where it is desired to remove the slivers 40 to enlarge the window openings; and while l have shown the laminar elements as nested together having their leg portions transverse to a strip of stock, it is not to be understood therefrom that such legs are necessarily cut across the grain of the stock. Such strips may well be sheared off transversely of a sheet of stock in order that the leg portions of the elements may have their longitudinal dimensions coincident with the general direction of the grain of the metal in the sheet of stock thereby producing laminations in which the core loss will be materially reducedu Likewise, the enveloping contour of the legs may, also be. altered and thereby alter the shape of the window produced, obtaining thereby other polygonally shaped windows instead of the generally trapezoidal shaped window shown in the drawing.

Having now described an embodiment of my invention which is at present the best means known to me for carrying the same into efi'ect, I would have it understood that this is merely illustrative, and that I do not mean to belimited thereby to the precise details shown nor restricted in the choice of recognized equivalents except as defined in my claims hereunto annexed.

What I claim as new and desire to secure by Letters Patent of the United States, is .1. A. pair of complementary L-shaped laminar elements of magnetic material adapted to form .a lamination suitable for assembly in cores of electrical apparatus, each element comprising a leg and a base, the leg of each having a diagonally cut awa corner, the base of each being shaped wit a triangular projection to be the enveloping complement of the leg of the other,

whereby the-laminar elements may be disposed in nested relation in the stock sheet of magnetic material.

element whereby the laminar elements may be disposed in nested relation.

3. A pair of complementary L-shaped laminar elements of etic material adapted to form a laminatlon suitable for assembly in cores of electrical apparatus, plement of the leg of the other whereby each element comprising a leg and a base, the laminar elements may be isposed in the leg of one element havmg an inner nested "relation in the stock of magnetic diagonally cut away corner, the leg of the material.

5 other element having an outer diagonally In witness whereof, I have hereunto set cut awa corner, the bases of each element my hand this seventh (7) da of rfigil 1921. being s aped to be the enveloping com- S. E. JO N SEN. 

